String matching with Grep


This maybe a very simple thing but somehow it is eluding me even after trying to run through the IGOR manuals and looking through the help topics. 

I am using Grep to match "Na2[15N]O3+" in a list. Igor is however matching Na2NO3+. I think IGOR is reading it like a regex expression in some shape or form but I don't understand why it is matching Na2NO3+ instead of Na2[15N]O3+. I want to force the program to match this formula with [15N] included in the string.

Would be thankful for your advice on how to pull this off. 



Here is a working example that may help:

String sList = "Na2[15N]O3+;Na2NO3+"
print GrepList(sList, "Na2[15N]O3+" )    // prints:     Na2NO3+;
print GrepList(sList, "Na2\[15N\]O3\+" ) // prints:     Na2[15N]O3+;
print ListMatch(sList, "Na2[15N]O3+")    // prints:     Na2[15N]O3+;

The first is my guess at the sort of thing you have a problem with.

The second escapes the GREP characters that have special meanings [, ], +

The third does not use GREP (but beware * if used can be wildcard characters).